Numerous systems use wireless technology in some manner, and antennas often play a major role in the performance of those systems. Various parameters of an antenna include bandwidth, directivity, gain, and impedance matching. One antenna implementation that achieves a good compromise among these parameters is a planar patch antenna.
For radar sensing applications (such as radar gauging for tank level measurements), antennas may need specific bandwidths and high directivity. High directivity is typically needed to reduce parasitic reflections from a storage tank's metallic walls. Radar sensing antennas also often need lower return losses and phase distortions to avoid incorrect level measurements, particularly at short distances. In addition, internal reflections due to surface waves inside the antennas often need to be minimized.
Conventional radar sensing systems often satisfy these criteria by decreasing a substrate height or using a low dielectric constant material (such as foam) in an antenna. However, decreasing the substrate height decreases antenna bandwidth. Also, the use of foam typically results in low production yields due to difficulties in controlling foam thickness, which increases manufacturing costs.